Wound treatment apparatus

ABSTRACT

A therapeutic apparatus for stimulating the healing of a wound site includes a polyurethane foam positioned at the wound site and a connector having a disc-like cup and an elbow-shaped spout. The connector is positioned in contact with the polyurethane foam, and the elbow-shaped spout is configured for connection to a tube that is capable of delivering negative pressure through the elbow-shaped spout and to the polyurethane foam. The therapeutic apparatus further includes a drape having a hole, the drape being positioned over the connector such that the elbow-shaped spout extends through the hole in the drape.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/713,485, filed Mar. 2, 2007, which is a continuation of U.S. patentapplication Ser. No. 09/613,497, filed Jul. 11, 2000, now U.S. Pat. No.7,316,672, which is a continuation of U.S. patent application Ser. No.09/078,223, filed on May 13, 1998, now U.S. Pat. No. 6,142,982, which isa continuation of International Application No. PCT/GB96/02802, filedNov. 14, 1996, which claims priority to British Patent Application No.GB9523253.4, filed Nov. 14, 1995. All of the above-mentionedapplications are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the healing of wounds and, more particularly,to apparatus for stimulating the healing of superficial wounds.

2. Description of Related Art

PCT Application No. GB95/01983 (WO 96/05873) describes apparatus forstimulating the healing of wounds comprising a porous pad which ispermeable to fluids for introduction into the wound, a dressing forcovering the wound and providing an air-tight seal around the wound, adrainage tube connecting the pad to a suction pump so that negativepressure can be applied to the wound to draw fluids therefrom, and acanister for collecting fluids sucked from the wound. The apparatusdescribed in the above application has proved to be clinically effectivebut there are some limitations in its use.

The apparatus described in the above PCT application is effective fortreating a wide variety of different types and sizes of wounds. However,it may require the patient to undergo treatment on the apparatus for along period. In cases where the patient is confined to bed this may notbe a major problem but where the patient is mobile it means that he orshe would be confined for long periods while the treatment takes place.

SUMMARY

According to one aspect of the present invention there is provided aportable therapeutic apparatus for stimulating the healing ofsuperficial wounds in a person, which comprises a housing containing asuction pump and a canister for containing fluids drawn from the woundby said pump, said canister including means for connection to a dressingin the region of the wound and a harness or belt for supporting thehousing on the person.

Typically, the housing will have a curved surface on the side intendedto be supported against the person's body so as to make the apparatusmore comfortable to wear. In addition, controls and indicatorsindicating the status of the treatment being applied to the wound arepreferably located on the supper side of the housing so that the patientcan easily see, e.g. the level of suction pressure being applied and theprogram for such treatment.

The suction pump is conveniently driven by an electric motor andbatteries for such motor being contained within the housing. However, itis generally more convenient to provide a separate housing for thebatteries since these can be placed on the belt or harness in such a wayas to balance the weight of the housing, preferably in a housing shapedsimilarly to the housing for the pump and canister.

The canister should be removably mounted within the housing, e.g. bymeans of a latch or similar release mechanism, so that the canister canbe readily removed and replaced when full.

In a portable therapeutic apparatus (in contrast with a static apparatusof the kind described in the above PCT application which cannot beeasily carried by the patient), it is less easy to determine thepressure prevailing at the wound site being treated. This is because thepressure will depend, in part, upon the hydrostatic height between thepump and the wound being treated and this height may vary during thetreatment, depending upon the patient's movements. Apparatus inaccordance with the invention overcomes this problem by providing anadditional conduit connecting the wound site or an area close thereto toa pressure-detecting means, preferably located in the housing. Thepressure-detecting means can be linked to a microprocessor programmed tomaintain such pressure within a predetermined range irrespective of themovement of the patient. This can be done by, for example, signaling thepump to increase its speed where the hydrostatic pressure increasesbetween the pump and the wound site or, conversely, reducing its speedwhere the hydrostatic pressure is reduced. This feature can also be usedin a static therapeutic apparatus of the kind described in theabove-mentioned application.

In the apparatus described in the above PCT application, the level ofliquid in the canister is monitored by capacitance measurement. It hasnow been found that a simpler way of determining when the canister isfilled is by measuring or detecting the pressure drop across thecanister. The pressure drop can be increased by providing a filterbarrier in the region of the outlet end of the canister.

Thus, when the liquid reaches a level within the canister so as tosubstantially occlude the filter, a sharp pressure change occurs in theconduit between the canister and the pump. By monitoring this pressurechange, the point at which the canister is filled can be accuratelydetermined.

Other features which are considered as characteristic for the inventionare set forth in the appended claims.

Although the invention is illustrated and described herein as embodiedin a wound treatment apparatus, it is nevertheless not intended to belimited to the details shown, since various modifications and structuralchanges may be made therein without departing from the spirit of theinvention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however,together with additional objects and advantages thereof will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic layout of the apparatus in accordance with theinvention,

FIGS. 2A and B are pictorial representations of the housing of the pumpand canister,

FIGS. 3A and B are pictorial representations of the apparatus supportedon a belt and harness, respectively,

FIG. 4 is an exploded view of the housing showing the contents,

FIGS. 5A to 5F show various views of a preferred form of the canisterand a section of a multi-lumen tube,

FIGS. 6A to 6D show various views of a foam dressing connector forconnecting the housing to the dressing,

FIG. 6E shows a section of a modified multi-lumen tube, and

FIGS. 7A and 7B show a plan and perspective view of a surgical drape foruse with the apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, the portable therapeutic apparatus comprisesa housing 210 (best shown in FIGS. 2A and 2B), having rounded cornersand a side 211 which is concavely curved in order to fit comfortably tothe wearer's body.

The shaping of the housing with curved surfaces is to avoid sharpcorners or edges which could dig in to the user or his career. Thesupper surface 212 is generally flat and has an LCD screen 213 on whichdetails such as applied pressure can be displayed. Control buttons 214are provided to adjust pressures and treatment intervals. Provision ismade for housing a canister within the housing and a snap release cover215 is arranged for removing or introducing the canister.

FIGS. 3A and 3B show schematically ways in which the housing 210 may besupported on the patient's body. In FIG. 3A the housing 210 is supportedon a belt 216 and its weight is balanced by a similarly rounded casing217 containing a rechargeable battery pack. FIG. 3B shows an alternativearrangement in which the housing is supported on a harness 218 and againa battery pack is contained in a housing 219, also supported on theharness.

FIG. 4 shows an exploded view of the housing 210 indicating the maincomponents within the housing. The housing consists of front and rearshell mouldings 1 and 2 having an external bet clip 21 for attachment toa belt or harness.

Within the housing shell 1 is located a suction pump 6 with associatedelectric motor 6A and the pump is connected by a silicon rubber tube 103to a canister spigot 7A in a cavity 20 for the canister 100. Alsoconnected to a second canister spigot 7B via a tube 10 is a pressurerelief valve and both tubes 103 and 10 are connected via T-connectors Tto pressure transducers (not shown). A microprocessor 4 is mounted on aPCB board S and a membrane assembly 3 incorporates an LCD indicator andcontrol buttons.

The apparatus may include means for recording pressures and treatmentconditions given to a particular patient which may be printed outsubsequently by the physician. Alternatively, the equipment may includea modem and a telephone jack so that the conditions under which thepatient has been treated can be interrogated by the physician from adistant station.

Canister 100 is a push fit into the cavity 20 and its lower end issupported in a cover 30. The cover 30 incorporates fingers 31 which arereleasably engageable with lips 32 to hold the canister in position. Thecanister and the latch mechanism is arranged so that when the latch isengaged, the spigots 7A and 7B are in sealing engagement or abutmentwith tubular protrusions 33 and 34 formed in the top of the canister.

The method of operation of the apparatus can be appreciated from theschematic layout in FIG. 1, in which the canister 100 is connected viatube 101 to a porous dressing 102 at the wound site. Suction is appliedto the wound site via the canister by a tube 103, connected to the pump6. The pressure in the tube 103 is detected by the transducer 105.

A second tube 106 is connected to the wound site 102 at one end, andalso to a pressure relief valve 8 and to a second transducer 108. Tubes106 and 101 can be combined in a multi-partitioned tube in a manner tobe described later. By means of tube 106 and transducer 108 the pressureat the wound site can be measured or monitored. A filter 109 is placedat or close to the outlet end of the canister 100 to prevent liquid orsolid particles from entering the tube 103. The filter is a bacterialfilter which is hydrophobic and preferably also lypophobic.

Thus, aqueous and oily liquids will bead on the surface of the filter.During normal use there is sufficient air flow through the filter suchthat the pressure drop across the filter is not substantial.

As soon as the liquid in the canister reaches a level where the filteris occluded, a much increased negative pressure occurs in tube 103 andis detected by transducer 105. Transducer 105 is connected to circuitrywhich interprets such a pressure change as a filled canister and signalsthis by means of a message on the LCD and/or buzzer that the canisterrequires replacement. It may also automatically shut off the working ofthe pump.

In the event that is desired to apply intermittent suction to the woundsite, a pressure relief valve 8 enables the pressure at the wound siteto be brought to atmospheric pressure rapidly. Thus, if the apparatus isprogrammed, for example, to relieve pressure at 10 minute intervals, atthese intervals valve 8 will open for a specified period, allow thepressure to equalize at the wound site and then close to restore thesuction. It will be appreciated that when the constant suction (ornegative pressure) is being applied to the wound site, valve 8 remainsclosed and there is no leakage from atmosphere. In this state, it ispossible to maintain negative pressure at the wound site without runningthe pump continuously, but only from time to time, to maintain a desiredlevel of negative pressure (i.e. a desired pressure below atmospheric),which is detected by the transducer 105. This saves power and enablesthe appliance to operate for long periods on its battery power supply.

Instead of running two separate tubes to the wound site, it ispreferable to contain tubes 106 and 101 in a single tube which isconnected through the canister.

Thus, for example, tubes 103 and 101 may comprise an internal tubesurrounded by an annular space represented by tube 106. This isillustrated in FIGS. 5A to 5F and in a modified form of FIG. 6E.

In an alternative embodiment, the multi-lumen tube may be constructed asshown in FIG. 6E. In this embodiment, the internal bore 606 comprisesthe line 101 (see FIG. 1) and is used to extract fluids from the woundsite. Air flow (represented by line 106 in FIG. 1) passes down conduits607 located within the walls of the tube. By spacing the conduits 607 at90° intervals around the tube, the risk of arresting the air flow bykinking or twisting the multi-lumen tube is minimized.

FIG. 5E is a plan view of the top of a preferred shape of canister, thegenerally triangular shape in section being chosen to fit better thespace within the cavity 20 (see FIG. 4). Tubular protrusions on the topof the canister are connected internally of the canister withrespectively conduits 124 and 121 (see sectional view of FIG. 5B), thusmaintaining a separation between the tubes which are represented bylines 103 and 106 in FIG. 1. At the base of the canister, a moulding 125facilitates connection to a multi-partitioned tube 126 shown in FIG. 5F.Tube 126 has a central bore 127 which is sized to fit over a spigot 128in moulding 125. At the same time, the external wall of tube 126 sealsagainst the inner wall 129 of moulding 125. Thus, compartment 124 willconnect with central bore 127 and the compartment 121 will connect withthe annular spaces 130 of tube 126. In this way, a conduit 130corresponds with line 106 and central bore 127 with line 101 as shown inFIG. 1.

The partitioned tube need not continue all the way to the wound site102, but can be connected to a short section of single bore tube closeto the wound site.

In the event of an air leak in the dressing at the wound site 102, thiscan be detected by both transducers 105 and 108 reading sufficientnegative pressure for a specific time period and then triggering a leakalarm, i.e. a message on the LCD, preferably also with an audiblewarning.

Typically, the pump 6 is a diaphragm pump but other types of pumps andequivalent components to those specifically employed may be substituted.

FIGS. 6A-6D show various views of a connector for attaching themulti-lumen tube at the wound site. FIG. 7A and 7B show a plan andperspective view of a surgical drape for attaching the connector to aporous dressing at the wound site. The connector comprises a mouldedplastics disc-like cup 601 having a centrally positioned spout 602. Thespout 602 is sized to accept, as a closely sliding fit, the end of amulti-lumen tube, e.g., of the kind shown in FIGS. 5F or 6E.

In use, a porous dressing is cut to correspond with the extent of thewound and pressed onto the wound as shown in FIG. 10 of our above citedPCT application WO 96/05873. Instead of introducing the lumen into thefoam dressing, the cup 601 is pressed onto the porous dressing andsecured by a surgical drape. However, if desired, the end of the lumencan be passed into the spout and additionally pressed into the foam. Asurgical drape such as shown in FIGS. 7A and 7B, can be used to securethe connector, lumen and dressing. The drape comprises a polyurethanefilm 701 coated on one side with a pressure-sensitive acrylic resinadhesive. A hole 702 is cut through all layers of the drape and the holeis dimensioned to correspond approximately with the outer cross-sectionof the spout 602. Film 701 has an overall size which allows it to beadhered to the patient's skin around the wound site, while at the sametime, securing the connector to the porous dressing. A sufficientoverlap around the wound is provided so that an airtight cavity isformed around the wound.

In an alternative form, the drape can be made in two parts, e.g. bycutting along the line X-X in FIG. 7A. With this arrangement, the woundcan be sealed by overlapping two pieces of surgical drape so that theyoverlap each other along a line Y-Y as shown in FIG. 6D.

The surgical drape may include a protective film 703, e.g. ofpolyethylene, and a liner 704 which is stripped off prior to use toexpose the pressure-sensitive adhesive layer. The polyurethane film mayalso include handling bars 705, 706, which are not coated with adhesive,to facilitate stretching of the film over the wound site. The dressingis preferably a pad of porous, flexible plastics foam, e.g. reticulated,open intercommunicating cellular flexible polyurethane foam, especiallyof the kind described in the above-mentioned PCT Application WO96/05873.

Alternatively, a reticulated intercommunicating cellular foam made fromflexible polyvinylacetate or polyvinylalcohol foam may be used. Thelatter is advantageous because it is hydrophilic. Other hydrophilic opencelled foams may be used.

In another method of therapy, the foam dressing may be sutured into awound after surgery and the foam dressing connected to the pump unit bythe multi-lumen catheter. Negative pressure can then be appliedcontinuously or intermittently for a period determined by the surgeon,e.g. from about 6 hours to 4 to 5 days. After this period, the dressingis removed and the wound re-sutured.

This therapy improves the rate of granulation and healing of woundsafter surgery.

1. A therapeutic apparatus for stimulating the healing of a wound site,the apparatus comprising: a polyurethane foam positioned at the woundsite; a connector having a disc-like cup and an elbow-shaped spout, theconnector being positioned in contact with the polyurethane foam, theelbow-shaped spout configured for connection to a tube capable ofdelivering negative pressure through the elbow-shaped spout and to thepolyurethane foam; and a drape having a hole and the drape beingpositioned over the connector such that the elbow-shaped spout extendsthrough the hole in the drape.
 2. The apparatus of claim 1, wherein thedrape includes an adhesive on one side of the drape.
 3. The apparatus ofclaim 2 further comprising a liner positioned on the adhesively-linedside of the drape to protect the adhesive prior to use.
 4. The apparatusof claim 1, wherein the drape is sized to extend beyond the polyurethanefoam such that the drape is capable of being secured to skin surroundingthe wound site.
 5. The apparatus of claim 1, wherein the drape isadhesively secured to the connector, the polyurethane foam, and skinsurrounding the wound site.
 6. The apparatus of claim 5, wherein thedrape maintains negative pressure at the wound site.
 7. The apparatus ofclaim 1, wherein the drape further comprises: a polyurethane film havinga pressure-sensitive adhesive on a portion of a first side of thepolyurethane film, the polyurethane film having handling bars that arenot coated with adhesive to facilitate placement of the polyurethanefilm over the wound site; a protective film disposed on a second side ofthe polyurethane film; and a liner removably positioned on theadhesively-lined, first side of the polyurethane film.
 8. The apparatusof claim 1, wherein the polyurethane foam is an open-celled, reticulatedfoam.
 9. The apparatus of claim 1, wherein the elbow-shaped spout iscentrally positioned on the disc-like cup.
 10. A therapeutic apparatusfor stimulating the healing of wound site, the apparatus comprising: aporous dressing positioned at the wound site; a connector having aflange and a centrally positioned spout, the flange having a lowersurface and a substantially-planar upper surface, the connector beingpositioned adjacent the polyurethane foam, the centrally positionedspout adapted to be connected to a tube capable of delivering negativepressure through the centrally positioned spout; and a drape configuredto secure the connector to the porous dressing, the drape having anaperture and the drape being positioned over the connector such that thecentrally positioned spout extends through the aperture in the drape.11. The apparatus of claim 10, wherein the porous dressing is anopen-celled, reticulated, polyurethane foam.
 12. The apparatus of claim10, wherein the porous dressing is a polyvinyl alcohol foam.
 13. Theapparatus of claim 10, wherein the lower surface of the flange is incontact with the porous dressing.
 14. The apparatus of claim 10, whereinthe drape includes an adhesive on one side of the drape.
 15. Theapparatus of claim 14 further comprising a liner positioned on theadhesively-lined side of the drape to protect the adhesive prior to use.16. The apparatus of claim 10, wherein the drape is adhesively securedto the substantially-planar upper surface of the flange.
 17. Theapparatus of claim 10, wherein the drape is sized to extend beyond theporous dressing and is adhesively secured to the skin surrounding thewound site.
 18. The apparatus of claim 10, wherein the drape isadhesively secured to the connector, the porous dressing, and skinsurrounding the wound site.
 19. The apparatus of claim 18, wherein thedrape maintains negative pressure at the wound site.
 20. The apparatusof claim 10, wherein the drape further comprises: a polyurethane filmhaving a pressure-sensitive adhesive on a portion of a first side of thepolyurethane film, the polyurethane film having handling bars that arenot coated with adhesive to facilitate placement of the polyurethanefilm over the wound site; a protective film disposed on a second side ofthe polyurethane film; and a liner removably positioned on theadhesively-lined, first side of the polyurethane film.
 21. The apparatusof claim 10, wherein the centrally positioned spout is elbow-shaped. 22.The apparatus of claim 10, wherein the centrally positioned spout isangled at a substantially right angle.
 23. A method for securing asuction device to a wound site, the method comprising: applying aconnector to an open-celled polymer foam positioned at the wound sitesuch that a flange of the connector contacts the open-celled polymerfoam, the connector having a centrally-positioned spout configured toreceive a suction tube; and sealing the connector at the wound site witha drape such that the centrally-positioned spout extends through a holeof the drape.
 24. The method of claim 23 further comprising: prior toapplying the suction head, positioning the open-celled polymer foam atthe wound site.
 25. The method of claim 23, wherein sealing theconnector at the wound site further comprises: adhesively securing thedrape to the flange of the connector, the open-celled polymer foam, andskin surrounding the wound site.
 26. The method of claim 23, whereinsealing the connector at the wound site further comprises: stretchingthe drape over the connector and the open-celled polymer foam; andadhesively securing the drape to skin surrounding the wound site. 27.The method of claim 23, wherein the open-celled polymer foam is areticulated, polyurethane foam.
 28. The method of claim 23, wherein theopen-celled polymer foam is a polyvinyl alcohol foam.
 29. A method foradministering negative pressure wound site therapy to a wound site, themethod comprising: positioning an open-celled polymer foam at the woundsite; applying a connector having a flange and a centrally-positionedspout to the open-celled polymer foam such that a flange of theconnector contacts the open-celled polymer foam; securing the connectorat the wound site with a drape such that the centrally-positioned spoutextends through a hole of the drape; and applying a negative pressure tothe wound site through the centrally-positioned spout and open-celledpolymer foam.
 30. The method of claim 29 further comprising: maintainingthe negative pressure at the wound site with the drape positioned overthe connector.
 31. The method of claim 29, wherein sealing the suctionhead at the wound site further comprises: adhesively securing the drapeto the flange of the connector, the open-celled polymer foam, and skinsurrounding the wound site.
 32. The method of claim 29, wherein sealingthe connector at the wound site further comprises: stretching the drapeover the connector and the open-celled polymer foam; and adhesivelysecuring the drape to skin surrounding the wound site.
 33. The method ofclaim 29, wherein the open-celled polymer foam is a reticulated,polyurethane foam.
 34. The method of claim 29, wherein the open-celledpolymer foam is a polyvinyl alcohol foam.